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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

4252 results found.

  1. GRB 231129A: optical upper limit in Mondy observatory
  2. GRB 231129C: AstroSat CZTI detection
  3. GRB 231129C: CALET Gamma-Ray Burst Monitor detection
  4. GRB 231129C: Fermi GBM Observation of a very bright GRB
  5. GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
  6. GRB 231129C: MAXI/GSC detection
  7. GRB 231129C: BALROG localization (Fermi Trigger / GRB 231129799)
  8. GRB 231129C: Fermi GBM detection of a very bright burst
  9. GRB 231129C: Fermi GBM Final Real-time Localization
  10. Fermi trigger No 722977823: Global MASTER-Net observations report
  11. GRB 231129B: MAXI/GSC detection
  12. Integral GRB231129.21: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
  14. Fermi trigger No 722507896: Global MASTER-Net observations report
  15. Fermi trigger No 722462310: Global MASTER-Net observations report
  16. Fermi trigger No 722349867: Global MASTER-Net observations report
  17. GRB 231117A : MITSuME Akeno optical afterglow candidate detection
  18. GRB 231118A: Fermi GBM Final Real-time Localization
  19. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  20. GRB 231117A: AKO Optical Upper Limit
  21. Swift GRB 231117A: Global MASTER-Net observations report
  22. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  23. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  24. GRB 231115A: archival HST observations
  25. GECAM-B observation of a short burst from SGR J1555-5402
  26. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  27. GRB 231111A: GMG observation (correction)
  28. GRB 231111A: GMG observation upper limit
  29. Fermi GRB 231108A: Global MASTER-Net observations report
  30. Fermi GRB 231106A: Global MASTER-Net observations report
  31. GRB 231104A: 3.6m DOT optical upper limit
  32. Fermi GRB 231103A: Global MASTER-Net observations report
  33. GRB 231104A: Fermi-LAT detection
  34. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  35. IceCube Alert 231103.39: Global MASTER-Net observations report
  36. Fermi trigger No 720498201: Global MASTER-Net observations report
  37. GRB 231024A: AKO Optical Counterpart Candidate
  38. Fermi GRB 231030A: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  40. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  43. Fermi trigger No 720224759: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
  46. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  47. LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
  48. LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
  49. Fermi GRB 231019A: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
  51. GRB 230827B: 10.4m GTC spectroscopic redshift
  52. LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  54. IPN triangulation of GRB 230919A (short)
  55. transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
  56. LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  58. IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 230911A: Swift-XRT afterglow detection
  60. Fermi trigger No 716449174: Global MASTER-Net observations report
  61. IceCube Alert 230914.22: Global MASTER-Net observations report
  62. GRB 230911A: GOTO optical counterpart candidate
  63. GRB 230906A: Chandra detection of the X-ray afterglow
  64. GRB 230903A: VLT/X-shooter optical observations
  65. GRB 230904C: Fermi GBM Final Localization
  66. Fermi GRB 230903A: Global MASTER-Net observations report
  67. GRB 230904B is not a GRB
  68. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  69. GRB 230828A: AstroSat CZTI detection
  70. GRB 230828A: GRBAlpha detection
  71. Swift Trigger 1188089 is not a GRB
  72. Fermi GRB 230827A: Global MASTER-Net observations report
  73. GRB 230824A: AKO Photometric Follow-up Observations
  74. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  75. GRB 230818B: VZLUSAT-2 detection
  76. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  77. GRB 230818A: SAO RAS Zeiss-1000 observations
  78. Fermi GRB 230818A: Global MASTER-Net observations report
  79. GRB 230818A: Swift detection of a burst
  80. Fermi GRB 230817A: Global MASTER-Net observations report
  81. GRB 230816A: TShAO and Assy optical observations
  82. GRB 230816A: SAO RAS optical observations
  83. IPN triangulation of GRB 230815B
  84. GRB 230812B: Fermi-LAT detection
  85. GRB 230812B: Fermi GBM Observation of a very bright burst
  86. LAT GRB230812.79: Global MASTER-Net observations report
  87. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  88. LIGO/Virgo/KAGRA S230802aq: AstroSat CZTI non-detection and upper limits
  89. IceCube-230724A: JCMT/SCUBA-2 submm observations
  90. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  91. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate
  93. IceCube Alert 230724.08: Global MASTER-Net observations report
  94. GRB 230724A: Fermi GBM Final Real-time Localization
  95. Fermi trigger No 711805358: Global MASTER-Net observations report
  96. Fermi GRB 230723A: Global MASTER-Net observations report
  97. GRB 230707A: Fermi GBM Detection
  98. Fermi GRB 230707A: Global MASTER-Net observations report
  99. Fermi trigger No 710117592: Global MASTER-Net observations report
  100. GRB 230628E: ATCA rapid radio follow-up

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